import java.util.Stack;

public class MyQueueUseStack {
    Stack<Integer> s1;
    Stack<Integer> s2;

    public MyQueueUseStack() {
        s1 = new Stack<>();
        s2 = new Stack<>();
    }

    public void push(int x) {
        s1.push(x);
    }

    public int pop() {
        if(empty())
            return -1;
        if(s2.isEmpty())
            while(!s1.isEmpty())
                s2.push(s1.pop());
        return s2.pop();
    }

    public int peek() {
        if(empty())
            return -1;
        if(s2.isEmpty())
            while(!s1.isEmpty())
                s2.push(s1.pop());
        return s2.peek();
    }

    public boolean empty() {
        return s1.isEmpty() && s2.isEmpty();
    }
}
